1. Field of the Disclosure
The disclosure herein relates in general to processes for the chromium oxyfluoride catalyzed dehydrofluorination of hydrofluorocarbons to make hydrofluoroolefins. More particularly, the disclosure herein relates to the chromium oxyfluoride catalyzed dehydrofluorination of hydrofluoropropanes to make hydrofluoropropenes.
2. Description of Related Art
As a result of the Montreal Protocol phasing out ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), industry has been working for the past few decades to find replacement refrigerants. The solution for most refrigerant producers has been the commercialization of hydrofluorocarbon (HFC) refrigerants. The new hydrofluorocarbon refrigerants, HFC-134a being the most widely used at this time, have zero ozone depletion potential and thus are not affected by the current regulatory phase out as a result of the Montreal Protocol. The production of other hydrofluorocarbons for use in applications such as solvents, blowing agents, cleaning agents, aerosol propellants, heat transfer media, dielectrics, fire extinguishants and power cycle working fluids has also been the subject of considerable interest.
There is also considerable interest in developing new refrigerants with reduced global warming potential for the mobile air-conditioning market.
Tetrafluoropropenes and pentafluoropropenes, both having zero ozone depletion and low global warming potential, have been identified as potential refrigerants. European Patent Application EP 726 243 discloses a process for the manufacture of 1,2,3,3,3-pentafluoropropene (HFC-1225ye) by the dehydrofluorination of 1,1,1,2,3,3-hexafluoropropane (HFC-236ea). The dehydrofluorination is done in the vapor phase in the presence of a trivalent chromium oxide or partly fluorinated trivalent chromium oxide catalyst.
There is a need for new manufacturing processes for the production of tetrafluoropropenes and pentafluoropropenes.
HFC-1225ye may exist as one of two configurational isomers, E or Z, which boils at different temperatures. It has been identified that Z isomer is preferable as a refrigerant. Thus, there is a need for manufacturing processes for the HFC-1225ye productions with a high Z/E ratio.